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For the MPE-SR formulation, we consider DKo = {mT (·) : T Tfull}, the dictio-nary
of transformations with Ko levels of decomposition, where from Section 3.2.1 the
approximated MPE-SR reduces to the following cost-fidelity problem,
Tk = arg max
T Tfull
|T| k
I (mT (X); Y ), (3.6)
8k 2
1, ..., |Tfull| = 2Ko
. The solution of this problem turns to finding the sub-band
decomposition of X that maximizes the empirical MI for a given number of frequency
bands, which can be seen as an optimal band allocation problem. Note that without
some additive property on the tree functionals involved in (3.6), an exhaustive search
is needed for solving it, which grows exponentially with the size of the problem. The
next subsections derive general sufficient conditions to address this problem using DP
techniques.
3.4.1 Tree-Embedded Feature Representation Results
We begin with some basic tree-embedded properties of our dictionary of feature rep-resentations.
To simplify notation let (T) = I (mT (X); Y ) denote our target MI tree
functional, and Xl
j = Ml
j(X) denote the random measurement of X in the subspace Xl
j
in (3.5).
Proposition 3.1 The collection {mT (X) : T Tfull} is embedded in the sense that,
H(Xl
j |Xl+1
2j ,Xl+1
2j+1) = 0, 8(l, j) 2 I(Tfull). (3.7)
50
Object Description
| Title | On optimal signal representation for statistical learning and pattern recognition |
| Author | Silva, Jorge |
| Author email | jorgesil@usc.edu; josilva@ing.uchile.cl |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Electrical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2008-06-23 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-21 |
| Advisor (committee chair) | Narayanan, Shrikanth S. |
| Advisor (committee member) |
Kuo, C.-C. Jay Ordóñez, Fernando I. |
| Abstract | This work presents contributions on two important aspects of the role of signal representation in statistical learning problems, in the context of deriving new methodologies and representations for speech recognition and the estimation of information theoretic quantities.; The first topic focuses on the problem of optimal filter bank selection using Wavelet Packets (WPs) for speech recognition applications. We propose new results to show an estimation-approximation error tradeoff across sequence of embedded representations. These results were used to formulate the minimum probability of error signal representation (MPE-SR) problem as a complexity regularization criterion. Restricting this criterion to the filter bank selection, algorithmic solutions are provided by exploring the dyadic tree-structure of WPs. These solutions are stipulated in terms of a set of conditional independent assumptions for the acoustic observation process, in particular, a Markov tree property across the indexed structure of WPs. In the technical side, this work presents contributions on the extension of minimum cost tree pruning algorithms and their properties to affine tree functionals. For the experimental validation, a phone classification task ratifies the goodness of Wavelet Packets as an analysis scheme for non-stationary time-series processes, and the effectiveness of the MPE-SR to provide cost effective discriminative filter bank solution for pattern recognition.; The second topic addresses the problem of data-dependent partitions for the estimation of mutual information and Kullback-Leibler divergence (KLD). This work proposes general histogram-based estimates considering non-product data-driven partition schemes. The main contribution is the stipulation of sufficient conditions to make these histogram-based constructions strongly consistent for both problems. The sufficient conditions consider combinatorial complexity indicator for partition families and the use of large deviation type of inequalities (Vapnik-Chervonenkis inequalities). On the application side, two emblematic data-dependent constructions are derived from this result, one based on statistically equivalent blocks and the other, on a tree-structured vector quantization scheme. A range of design values was stipulated to guarantee strongly consistency estimates for both framework. Furthermore, experimental results under controlled settings demonstrate the superiority of these data-driven techniques in terms of a bias-variance analysis when compared to conventional product histogram-based and kernel plug-in estimates. |
| Keyword | signal representation in statistical learning; Bayes decision theory; basis selection; tree-structured bases and Wavelet packet (WP); complexity regularization; minimum cost tree pruning; family pruning problem; mutual information estimation; divergence estimation; data-dependent partitions; statistical learning theory; concentration inequalities; tree-structured vector quantization. |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1684 |
| Contributing entity | University of Southern California |
| Rights | Silva, Jorge |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Silva-2450 |
| Archival file | uscthesesreloadpub_Volume32/etd-Silva-2450.pdf |
Description
| Title | Page 63 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | For the MPE-SR formulation, we consider DKo = {mT (·) : T Tfull}, the dictio-nary of transformations with Ko levels of decomposition, where from Section 3.2.1 the approximated MPE-SR reduces to the following cost-fidelity problem, Tk = arg max T Tfull |T| k I (mT (X); Y ), (3.6) 8k 2 1, ..., |Tfull| = 2Ko . The solution of this problem turns to finding the sub-band decomposition of X that maximizes the empirical MI for a given number of frequency bands, which can be seen as an optimal band allocation problem. Note that without some additive property on the tree functionals involved in (3.6), an exhaustive search is needed for solving it, which grows exponentially with the size of the problem. The next subsections derive general sufficient conditions to address this problem using DP techniques. 3.4.1 Tree-Embedded Feature Representation Results We begin with some basic tree-embedded properties of our dictionary of feature rep-resentations. To simplify notation let (T) = I (mT (X); Y ) denote our target MI tree functional, and Xl j = Ml j(X) denote the random measurement of X in the subspace Xl j in (3.5). Proposition 3.1 The collection {mT (X) : T Tfull} is embedded in the sense that, H(Xl j |Xl+1 2j ,Xl+1 2j+1) = 0, 8(l, j) 2 I(Tfull). (3.7) 50 |
